Guest Post: Here Come the Lithiums

Many thanks to SWLing Post contributor, Bob Colegrove, who shares the following:

Power Play – Here Come the Lithiums

by Bob Colegrove

I have belonged to several radio-oriented user groups in recent years and can’t help noticing how often the subject of batteries comes up.  It’s almost a sub-hobby within the hobby.  There are a couple of reasons for this, first is the unending quest for the ultimate cost-effective, everlasting battery, and second, it’s a rare opportunity for most of us to tinker in an increasingly complex world of technology.

Lithium batteries offer a sustainable voltage output well into their discharge cycle and can deliver a higher rate of current than alkaline batteries.  They are somewhat lighter in weight than alkaline batteries – 2.5 oz. versus 5 oz. for D-cells.

Considering the fast pace of technology, lithium batteries have been with us for a comparatively long time, this in the form of cell phone and camera power, not to mention a host of electric appliances.  Most of these batteries have limited purpose, that is they have been developed and packaged for just a few applications, thus resulting in an incredible variety of sizes and shapes, and no doubt a host of frustrations due to obsolescence.  It’s somewhat reminiscent of the early days of transistor radios which ran on a wide array of zinc-carbon batteries.

Perhaps I have been asleep at the wheel, but it has only come to my attention recently that lithium chemistry has begun to backfill the standard battery sizes we have long been familiar with, namely AAA, AA, C, D, and even the PP3 standard 9 volt.

I have been running along quite successfully for more than 10 years on AA NiMH technology on several portable radios.  Although these run at a slightly lower cell voltage of 1.25 Vdc, the one-for-one substitution of these for alkaline chemistry has seldom been a problem in terms of performance.  In most cases, newer radios are provided with an alkaline/NiMH-NiCad setting to compensate for the difference in voltage.  Even the venerable Sony ICF SW7600GR, for which alkaline batteries are assumed, seems to operate equally well either way.

My problem has always been the larger power consumers running on D-cells – the Sony ICF 2010 and Grundig Satellit 800 to cite two examples.  A fresh set of NiMH batteries put the 2010 on the cusp of poor performance.  Lithium batteries having a sustainable single-cell voltage of 1.5 Vdc now provide a possible alternative to a steady diet of costly alkaline cells.  Even more attractive, some are equipped with a USB-C connector and can be recharged without a dedicated charger.

In the figure above, a set of four lithium D cells are connected simultaneously through a 4-lead USB-C harness and USB charger (not shown).  Many of the brands include the harness with a set of batteries.  I have added a USB multimeter, which I find very useful to monitor the progress of the charge, but this is not necessary.  This particular meter can also show accumulated capacity.  However, it should be noted that, unless batteries are charged one at a time, charging rate and capacity will show the total values for the number of batteries being charged.  I would also recommend that the USB charger be rated at least 3 amps.  In the figure below, one of the USB-C leads is connected at the top of the battery.  The built-in LED flashes during charge and remains on when the charge is complete.

Cost is an equally important consideration.  There is a lot of hype in the marketing department about how many times these batteries can be recharged.  The key compound preposition here is “up to,” and as long as they use those words, they can make the number anything they want to.  That said, it simply won’t take more than a few cycles for the cost-benefit cusp to be reached in favor of lithium batteries.

I am just getting started with this.  Although the batteries came highly recommended for the portable radio application, I can make no judgment at this time as to their ultimate quality or convenience.  It just seems like the next logical way to go.

There are some things to remember when choosing lithium batteries.  Not all lithium batteries are rechargeable, particularly smaller sizes.  Some do not come with the built-in USB-C charging jack, so a separate charger intended for lithium batteries will be required.  D size batteries are also available at 3.6 Vdc/cell.  There may be other options, so watch out.  Be sure to thoroughly check the features of any batteries you consider.

I would close by warning that lithium batteries come with safety caveats regarding their transport, handling, use, charging, and disposal.  These precautions are all well stated in the literature, which should be followed with an abundance of caution.  Of note is the fact that not all chargers support lithium batteries, and their capability should be checked as well.

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17 thoughts on “Guest Post: Here Come the Lithiums

  1. Bob Colegrove

    OK my friends, I was determined and finally succeeded. I stand corrected and have eaten my large slice of humble pie. The Doublepow D-cells appear to use a noise-producing switching circuit in their power conversion. By placing a second radio tuned to 1700 kHz with its internal ferrite core antenna squarely against the line of lithium batteries, one can achieve some significant noise. This virtually disappears with the radios separated 3 to 4 inches. The “placebo” 2010 with alkaline batteries did not do this. The fact that the batteries are housed in metal cases and the RF circuitry of the Sony ICF-2010 is farther away and shielded probably contribute to the noise immunity. As my test was rather extreme, and out of sheer stubbornness, I have no immediate plans to relegate the Doublepows to a flashlight.

  2. Mike N7MSD

    I’ve seen these same comments on Amazon about these types of batteries and the problem is likely nothing to do with the BMS but rather that they all (have to have) switch-mode buck (DC-DC) converters to step down from the cell’s 3.7V+ to the required 1.5V and there is simply no way in hell you can put ferrite or whatever into such a tiny package.

    I’ve experienced this with an AnyTone AT-8×8 DMR HT battery eliminator where I couldn’t receive anything in the car & thought I damaged something! There was no whine, hiss, etc, just NOTHING. Replacing the eliminator with a regular battery pack made everything work again, which means the eliminator was putting out SO MUCH broadband RFI that it made the radio almost completely deaf (catastrophic desense) ON UHF!! (Could be the IF but still…)

    My advice if you want to use these would be only on radios you’re willing to open and then install some ferrite & feed-thru caps right on the battery leads as they leave the cell holder: no promise it’ll work but it’s the only idea I have. Otherwise, if the radio can take a higher voltage external power, wire up regular batteries to that.

    (Also as a reminder–though I’m sure everyone here knows this–many USB battery packs are horrible radiators as well! They’re not meant for the world below 30 MHz.)

    1. Bob Colegrove

      I think the problem here is with terms such as “must have” or “have-to-have” switching type DC-DC converters. Each time I read one of these replies I run to my ICF-2010 with three 1.5 Vdc Doublepow lithium batteries and search for the faintest indication of noise, RFI – whatever. Failing to find any problem, I honestly ask myself what am I missing. Even then I might have let the issue go, but my own experience came on the recommendation of two independent, respected, technically-competent radio enthusiasts who are apparently unaware there may be an issue. As I occasionally manage to bag the “D” beacon from Sevastopol with the above battery/radio combination, I remain open to the possibility that some manufacturers might just have come up with an effective solution.

  3. Bob Colegrove

    Final Thought – they seem to work fine.

    Be assured I have NOT experienced the “RFI” (noise) described in several comments to my posting, certainly not its total domination of medium wave and shortwave reception.

    Now, the comments having aroused some doubt about my own experience, I fired up a second ICF-2010 with alkaline batteries, and did a side-by-side test with the other 2010 with lithium D batteries. I checked numerous frequencies between 0.55 and 15 MHz both with and without antennas. Again, no indication of the slightest RFI or noise attributable to the lithium batteries.

    I understand the theory being postulated by some commentators. The native voltage of a lithium cell is about 3.6 volts. This must be down-converted to 1.5 Vdc for normal D-cell operation. The battery management system (BMS) in a lithium battery must do this. The comments assume the DC-DC conversion requires a switching operation like a wall wart, which we know produces a hostile environment for AM radios. Perhaps this was the experience of some readers. Maybe it was characteristic of some early or inexpensive versions of 1.5-volt lithium batteries.

    I can only conclude manufacturers such as Doublepow and Pale Blue must have partially mastered the science by applying other means to produce quiet 1.5-volt lithium batteries. Otherwise, a few of us are deluded by batteries which are not what they are purported to be. In either case, the 1.5-volt/cell batteries I’m using seem to be an operational improvement over NiMH/NiCad technology and a cost improvement over alkalines.

  4. Thomas Post author

    For what it’s worth, I have Blue Planet versions of AA cells that I use in my Elecraft KX1 and (with adapters) in my solid state radios. I don’t have D or C cell versions, but adapter bodies that allow the AAs to work.

    I’ve experienced no RFI from the cell BMS systems that I’ve noticed–at least, not in the areas where I listen and operate on HF.

    I’ve spoken with Bob and his experince has been the same.

    I suspect QRM all has to do with the quality of the cells and BMS’s.


  5. Jason

    These batteries in my experience destroy MW listening. The RFI is so strong that it blows away the entire AM/MW broadcast band. It is impossible to get even a strong local and forget any DX.

    Regular alkaline AA and AAA batteries have become so cheap now that I use these in most of my radios. They can be transported safely, even on a plane. They also last longer before needing to be replaced (compared to how long a NIMH battery lasts on a single charge).

    Newer radios which have in built lithium batteries or run on BL-5C batteries don’t have this issue. These radios run at a native 3.7 volts and having a 5V USB-C or MIcro-USB port on board for charging don’t seem to interfere with the AM/SW noise floor.

    Examples of these include the Retekess TR605, TR110, V112, PR12, TR103, etc. XHDATA D-109. D-108, R-108, etc, Various Sihuadon radios and many more.

    The problems come when lithium batteries are stand ins for 1.5V batteries.

    1. Hank

      When I need to put D batteries into an older radio that does not get used every day I use the plastic adapter that surrounds two AA batteries and is the outer size of an Alkaline D battery.

      This has saved several of my radios from being damaged by Alkaline leaks.

      Panasonic brand Alkaline batteries have larger and more protective “expansion traps” inside to contain pasty liquids that corrode. Because of these traps Panasonic batteries have slightly less milliamp hour capacities than Duracell or Eveready – who are in a “Lasts Longer” advertising war.

      “Lasts Longer but leaks” is a horrible trade off.

  6. TomL

    I echo Mike S’s concern about an internal conversion circuit built into the battery. Li-ion chemistry demands a 3.7 volt output which necessitates the use of a DC conversion circuit to force voltage down to 1.5 volts – hence lots of RFI coming from the battery itself. Expect lots of noise if you use an internal whip antenna on a portable radio. Also, I notice it uses 5 volts to charge it, so that means that, yes, it is the typical 3.7 volt Li-ion battery with the DC conversion circuit built in. I also notice there are no examples of Li-ion 1.5 volt batteries in AA or AAA size form, probably because there is no room to fit the DC conversion circuit.

    I still prefer the NiMH batteries which are dead silent when using them and also much safer from explosion/burning. I do have one portable that uses the 18650 Li-ion battery but the radio is built to use the native 3.7 volts without the need to convert it.

  7. John Black

    I second MIke’s comment. Most of the radios I’ve tried to put those batteries in, including SW and VHF handhelds, received mostly RFI from the batteries and not much else. They seem to be useful for door locks and some similar things, but they also don’t give any indication that they are about to go dead….until they go dead.


      1. mangosman

        Mike, shows that the higher lithium voltage which is determined by what materials are used for the anode and cathode doesn’t change. This cell must contain a switchmode regulator to reduce the voltage to 1.5 V The size probably means there is little space for electronic filter components such as capacitors and inductors.
        The rated output is 3 Watt hours, the storage is 3.3 Watt hours so 9 % of the output is converted into heat by the switchmode regulator. Since the radio runs on 3.3 V it will need a boost switching regulator to increase the voltage causing more losses. Much better to use a Lithium Polymer battery which uses the battery without the losses of regulators. A native battery produces a steady DC voltage which is interference free!

        In summary, Xtar is producing a battery for old equipment designs. They produce expensive flashlights. The voltage of the high brightness white LEDs which are natively 3.5 V.

  8. Hank

    I have not used these USB-C plug rechargeable D cells, but I second the fire safety concerns with Li recharging. I place metal trays under Li batteries and chargers in power tool and cell phone charging situations.

    I will add that among the many names in NiMH rechargeable C or D batteries,
    only the Amazon branded NiMH batteries live up to their 10,000 and 5,000 milliamp hour ratings when tested on Opus BT-C2000 or LaCrosse Tech BC-9009 data recording chargers.

    Eneloop or Fijitsu AA or AAA NiMH also live up to ratings.
    Fijitsu bought the Japanese Sanyo Eneloop factory when Panasonic bought Sanyo years ago.

    Lithium battery technology continues to change rapidly.
    Toyota had a recent press release where they claim to have made breakthroughs.

    I did 6 years of graduate fuel cell research and know more details about electrolyte crystal structures than is good for mental health.

  9. mangosman

    I looked at 3 brands of digital radio receiver chips. (HDradio, DAB+ and DRM). Most modern receivers use microprocessors and receiver chips which operate at 3.3 V. A LiFePO4 cell has an electromotive force of a cell voltage when not producing current of 3.2 Volts. Thus no regulator is required. Standard lithium is 3.6 or 3.7 V Remember that the internal resistance rises as the cell becomes discharged. The voltage drop through this internal resistance is determined by Ohm’s law reducing the terminal voltage.
    Thus the voltage regulator on the processor and receiver chips can be a linear regulator which does not switch causing interference. Since the voltage drop is very small the power loss in such regulator is also very small.
    Switching regulators are required to charge the battery. In addition the charging current must be monitored to limit it when the battery is almost fully discharged and changing to constant voltage charging as the terminal voltage equals the EMF of the battery. Then the charger should switch off its output thus preventing fires.

    As for lithium fires the risk becomes higher as the amount of energy stored increases, particularly if it is being incorrectly charged. This is particularly a problem in poor quality batteries. and non matching charger characteristics. The most common type of lithium battery fires are in electric scooters and bikes.

    Shorts across batteries is also dangerous because the internal resistance can be very low allowing a very large current flow for a short time.

    Fire precautions from a fire department

  10. Mike S

    In my experience the rechargeable lithium cells providing regulated 1.5V output are unsuitable for LW/MW/SW radio listening.

    In order to bring the native voltage of a LIIon cell down to 1.5V, an internal buck converter is packaged inside. There is also a charging circuit which takes a nominal 4.2V – 5V input and replenishes the battery.

    The problem is that these circuits generate very strong broadband RFI – even when not being discharged – right inside your radio.

  11. Jock Elliott


    This is extremely helpful.

    I’d like to encourage to do an additional post on safety with Lithium batteries.

    I ask because a friend belongs to a club, one of whose members had a fire in a lithium battery that burned down his house. Unfortunately, I don’t have any additional details, but I would very much appreciate some safety tips.

    Cheers, Jock

    1. Jason VE3MAL

      The main things to know are that low quality suppliers often sell sketchy batteries online. That’s fine as a single cell, but poorly matched banks of cells can be a hazard. Those batteries above are likely single cells, so less of an issue.

      There are three situations that cause most fires. The most common is during charging. So it’s a good idea to charge anything you are not 100% confident in somewhere where a fire is containable. Second is physical damage. Protect these cells from being punctured and don’t abuse them. Last is during discharge, particularly at high currents. Buy batteries with over current protection circuits built in, and be careful to never short them. If it’s a large battery, you may want to stick a fuse right on the terminal as extra protection.


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